• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2019년도 춘계학술대회
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• pp.19-21
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• 2019

In this paper, we introduce VDES system and multipath channel model for maritime wireless digital communication. And we studied the influence of multipath for bit-error ratio performance by computer simulation. Next we propose time-domain adaptive equalizer to treat the influence of multipath, and review the simulation result for necessity of applying the adaptive equalizer.

• Journal of the Semiconductor & Display Technology
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• 제18권1호
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• pp.87-91
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• 2019

As a highly conductive and transparent electrode, ITO/Ag/ITO multilayers are fabricated using an in-line sputtering method. Optimal thickness conditions have been investigated in terms of the optical transmittance and the electrical conductance. Considering the optical properties, in this study, the experimental characteristics are analyzed based on theoretical phenomena, and they are compared with the simulated results. The simulations are based on the finite-difference-time-domain (FDTD) method in solving linear Maxwell equations. Consequently, the results showed that ITO/Ag/ITO multilayer structures with respective thicknesses of 39.2 nm/10.7 nm/39.2 nm are most suitable with an average transmittance of about 87% calculated for wavelengths ranging from 400-800 nm and a sheet resistance of about $7.1{\Omega}/{\square}$.

• Ocean Systems Engineering
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• 제9권2호
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• pp.179-190
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• 2019

This paper deals with the problem of the global stabilization for a class of ocean structure systems. It is well known that, in general, the global asymptotic stability of the ocean structure subsystems does not imply the global asymptotic stability of the composite closed-loop system. The classical fuzzy inference methods cannot work to their full potential in such circumstances because given knowledge does not cover the entire problem domain. However, requirements of fuzzy systems may change over time and therefore, the use of a static rule base may affect the effectiveness of fuzzy rule interpolation due to the absence of the most concurrent (dynamic) rules. Designing a dynamic rule base yet needs additional information. In this paper, we demonstrate this proposed methodology is a flexible and general approach, with no theoretical restriction over the employment of any particular interpolation in performing interpolation nor in the computational mechanisms to implement fitness evaluation and rule promotion.

• Journal of the Semiconductor & Display Technology
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• 제20권3호
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• pp.83-86
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• 2021

In this paper, electric fields in electromagnetic reverberation chambers, which are used as a substitute facility for EM-free anechoic chambers, are analyzed. This paper focused on the 4-5 GHz band, which is expected to adversely affect equipment. To analyze the field uniformity inside the electromagnetic reverberation chamber, electric field strengths are sampled and finite-difference time-domain method was used for numerical analysis. Moreover, Quadratic residue diffuser was used to improve the characteristics of the electromagnetic reverberation chamber and the uniformity of the internal field strength. Standard deviation, tolerance characteristics, and partiality characteristics were compared while varying the aiming point of transmission antenna.

• The Transactions of the Korean Institute of Power Electronics
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• 제26권4호
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• pp.302-305
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• 2021

Selection of the optimal inductance for power factor improvement of a buck AC/DC light-emitting diode (LED) driver with wide input voltage range is described in this study. The power factor change based on the slope compensation is obtained for various normalized output current (NOC) values using discrete-time domain analysis. The possibility of implementing constant slope compensation is described using power factor curves for various NOC values. NOC = 0.5 is chosen for the value of inductance with consideration for the simple implementation and reduction of inductor size. Experimental results of the inductance corresponding to NOC = 0.5 are presented.

• Journal of the Korean Society of Systems Engineering
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• 제17권2호
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• pp.106-113
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• 2021

Today, the market and customer requirements for safety-related products in the Railway industry are continuously increasing, and companies that supply these products continue to make related efforts. However, the international standard requirements for making safety-related products are high, so small and medium-sized business companies are having difficulty developing them due to problems in time and cost to achieve them. This study examined government-centered international certificate policies and cases and suggested improvement measures based on the research results. In addition to supporting international certification costs, the government needs to expand technical consulting and expert training for them to solve problems in obtaining an international certificate.

• Journal of Species Research
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• 제10권4호
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• pp.344-349
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• 2021

The purpose of this study was to isolate and identify wild yeasts from soil of Gyeongju city, and Haemadipsa rjukjuana of Gageodo Island, characterizing unrecorded yeast strains from Korea. The molecular analysis of the D1/D2 domain of 26S rDNA of yeast was performed using the Basic Local Alignment Search Tool (BLAST). No official report exists describing these three species: one species in the genus Candida, one species in the genus Debaryomyces, and one species in the genus Solicoccozyma. Candida saitoana YL9, Debaryomyces fabryi YL1, and Solicoccozyma terrea 20g9-1 are recorded for the first time from Korea. All three strains were oval shaped and polar binding, while positive for glucose, ᴅ-xylose, and ᴅ-cellobiose. Morphological, physiological, and biochemical properties are described in the species descriptions.

• 한국벤처창업학회:학술대회논문집
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• 한국벤처창업학회 2022년도 춘계학술대회
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• pp.157-161
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• 2022

Building on the DC interaction model between a parent company and its spin-offs, we examine that a dyadic relationship can be differentiated within the functions of space, motivation, and time. We investigate that these three factors encompassing the parent-spin-off DC relationship can be applicable to both linear(i.e., geographic proximity and low spin-off CEO's salary is positive) and nonlinear(i.e., too much frequency of new spin-off creation is as harmful as too little) effects on determining the performance of spin-off firms. The direction of causality is underpinned by social capital, human capital, and compensation-activation theory rather than by the normal consequences of previous empirical research. Further, our results suggest the overlap between DC and entrepreneurship; namely, spin-off firms create, learn, and exploit opportunities through a reconfiguration of parent DC so that DC establishes itself as a key concept in the entrepreneurship domain.

• Steel and Composite Structures
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• 제50권1호
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• pp.45-61
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• 2024

This research explores the domain of organic solar cells, a photovoltaic technology employing organic electronics, which encompasses small organic molecules and conductive polymers for efficient light absorption and charge transport, leading to electricity generation from sunlight. A computer simulation is employed to scrutinize resonance and dynamic stability in OSCs, with a focus on size effects introduced by nonlocal strain gradient theory, incorporating additional terms in the governing equations related to displacement and time. Initially, the Navier method serves as an analytical solver to delve into the dynamics of design points. The accuracy of this initial step is verified through a meticulous comparison with high-quality literature. The findings underscore the substantial impact of viscoelastic foundations, size-dependent parameters, and geometric factors on the stability and dynamic deflection of OSCs, with a noteworthy emphasis on the amplified influence of size-dependent parameters in higher values of the different layers' thicknesses.

• Journal of the Semiconductor & Display Technology
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• 제23권1호
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• pp.97-103
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• 2024

In this paper, the difference between the S-parameter and the characteristic impedance according to the structural change of the fine pitch coaxial socket was analyzed. A pitch of the probe pin was applied to 0.20mm, and ground pins of different conditions were placed on each of the five signal pins. Insertion loss and reflection loss were analyzed for the coaxial socket of normal structure and the two sockets of the proposed structure. In addition, the difference in characteristic impedance was analyzed using time domain reflectometry. Through the analysis, it was confirmed that the characteristic impedance was improved applying the new structures of the socket at the same pitch